WO2006049168A1

WO2006049168A1 - Polyvinyl alcohol film and method for producing same

Info

Publication number: WO2006049168A1
Application number: PCT/JP2005/020107
Authority: WO
Inventors: Seiichirou Hayakawa; Katsuhiko Katsuma; Akihiko Chigami
Original assignee: The Nippon Synthetic Chemical Industry Co., Ltd.
Priority date: 2004-11-02
Filing date: 2005-11-01
Publication date: 2006-05-11
Also published as: JP5089798B2; US20080113173A1; JP2011245872A; CN101056918B; JP2012058754A; CN101792535B; KR20120073366A; CN101792535A; KR101212424B1; TW200624477A; CN101056918A; KR20070083925A; JP4916589B2; KR101261772B1; TWI371461B

Abstract

Disclosed is a polyvinyl alcohol film having a film thickness of 30-70 μm and a kinetic friction coefficient against stainless-steel roll of not more than 0.03. Also disclosed is a method for producing such a polyvinyl alcohol film.

Description

Specification

Polybulal alcohol film and method for producing the same

Technical field

[0001] The present invention relates to a polyvinyl alcohol film. More specifically, the present invention relates to a polybulualcohol-based film excellent in transport performance and free from optical defects, and a method for producing the same.

Background art

Conventionally, a polyvinyl alcohol film is prepared by dissolving a polyvinyl alcohol resin in a solvent such as water to prepare a stock solution, and then forming the film by a solution casting method (hereinafter referred to as a casting method). In addition, it is manufactured by drying using a metal heating roll or the like. The polyvinyl alcohol film thus obtained is used in many applications as a film excellent in dyeing and adsorbing properties of dyes, and one of its useful applications is a polarizing film. Such a polarizing film is used as a basic component of a liquid crystal display, and in recent years, its use has been expanded to equipment requiring high quality and high reliability.

Under such circumstances, with the increase in the size of screens of liquid crystal televisions and the like, the size of the polarizing film, and hence the size of the polybulal alcohol film, which is the original film, is also increased. For example, polybulal alcohol film, which was lm wide until several years ago, has become the mainstream in the last few years, and products with a width of 3 m or more are already seen. Also, rolls that had been 2000m until a few years ago have now become 4000m long!

[0004] Along with such widening and lengthening, methods for producing polybulualcohol-based films have been improved. Many attempts have been made to improve the handling of the film itself by improving the polymerization degree and crystallization degree of polyvinyl alcohol-based resin, or the moisture content of the film, as well as improving the equipment. For example, a method for prescribing the water fraction in the film-forming process of a polyvinyl alcohol film (for example, see Patent Document 1) or a method for improving the stretchability by specifying the speed ratio between the winding device and the cast drum (for example, a patent Document 2) and methods for defining the coefficient of static friction of rolls in contact with polyvinyl alcohol films (for example, see Patent Document 3) have been proposed. However, even with these disclosed technologies, when a film is continuously transported by a roll “roll” roll, production may be delayed due to cracks or wrinkles, and polyvinyl alcohol may be used. Even if a film-based film can be obtained, rubbing between the roll and the film may cause fine scratches, and linear optical defects may be noticeable when a polarizing film is produced. In particular, when peeling powder is sprinkled on the product film surface for transportability and avoiding blocking

The optical defects of the polarizing film are remarkably observed. In both the production of polyvinyl alcohol films and the production of polarizing films, continuous production is usually carried out with a roll 'two' roll, and if production is stopped, much effort is required to restore the entire line. Is required. Therefore, in view of productivity, cost reduction in recent years, and optical performance, further improvement is desired in the method for producing a polybulual alcohol film!

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-28938

Patent Document 2: JP 2001-315141 A

Patent Document 3: Japanese Patent Application Laid-Open No. 2004-17321

Disclosure of the invention

Problems to be solved by the invention

[0007] An object of the present invention is to provide a polyvinyl alcohol film that is excellent in conveying performance and has no optical defects, and a method for producing the same, corresponding to widening and lengthening. Means for solving the problem

[0008] The inventors of the present invention have intensively studied to examine the above-mentioned problems. As a result, they have found that the above object can be achieved by the following production methods of polyvinyl alcohol film and polybulual alcohol film. It came to be completed. That is, the object of the present invention has been achieved by the following polybulal alcohol film and a method for producing the polybulal alcohol film.

(1) A polybule alcohol film having a film thickness of 30 to 70 μm and a dynamic friction coefficient of 0.03 or less against a stainless steel roll.

(2) The polybulualcohol-based film according to item (1), which contains polybulualcoholic rosin having a weight average molecular weight of 140000 to 260000.

(3) The polybutyl alcohol according to item (1), wherein the surface roughness (Ra) is 0.05 μm or less. Film.

(4) The polybutyl alcohol film according to item (1), wherein the film width is 2 m or more.

(5) The polybula alcohol-based Finolem according to Item (1), wherein the length of the film is 4000 m or more.

(6) The polybutyl alcohol film according to item (1), which is used as a raw film for a polarizing film.

(7) (A) a step of preparing a polybulualcohol aqueous solution containing 60% to 90% by weight of a surfactant containing a surfactant; From the above, a method for producing a polyvinyl alcohol film having a step of producing a polyvinyl alcohol film having a moisture content of 5% by weight or less, wherein the step of producing the polyvinyl alcohol film comprises the polyvinyl alcohol resin solution. A method for producing a polybulal alcohol-based film, wherein the evaporation rate of water is 15 to 30% by weight Z.

(8) The surfactant is a surfactant containing nitrogen, and the surfactant is contained in the polyvinyl alcohol-based aqueous resin solution in an amount of 0.01% by weight or more based on the polyvinyl alcohol-based resin. A method for producing a polybulualcohol-based film according to item (7).

(9) The method for producing a polyvinyl alcohol film according to item (7), wherein the surfactant is a nonionic surfactant containing nitrogen.

(10) (A) a step of preparing a polybulal alcohol-based aqueous resin solution containing a surfactant and having a moisture content of 60 to 90% by weight; and (B) the polybulal alcohol-based resinous resin by a casting method. A process for producing a polyvinyl alcohol film having a step of producing a polyvinyl alcohol film having a water content of 5% by weight or less from an aqueous solution, the process force for producing the polyvinyl alcohol film. The production of the polybulualcohol-based film is carried out so that the evaporation rate of water in the solution is 15 to 30% by weight Z, and the polyvinylalcoholic film is the polybulualcoholic film described in item (1) Method.

(11) The surfactant is a surfactant containing nitrogen, and the surfactant is The method for producing a polybulualcohol-based film according to item (10), wherein the polyvinylalcohol-based rosin aqueous solution contains 0.01% by weight or more with respect to the polyvinylalcohol-based rosin.

(12) The method for producing a polyvinyl alcohol film according to item (10), wherein the surfactant is a nonionic surfactant containing nitrogen.

(13) A polarizing film formed using the polybulualcohol-based film force according to item (1).

(14) A polarizing plate comprising the polarizing film according to item (13) and a protective film provided on at least one surface of the polarizing film.

The invention's effect

[0009] The polybulualcohol-based film of the present invention is excellent in transportability because of its high slipperiness with a small surface roughness and dynamic friction coefficient. Further, the polybula alcohol film of the present invention is a polybulualcohol film having no optical defects, and is effective as a raw film for a polarizing film.

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] The present invention relates to a polybutyl alcohol film having a film thickness of 30 to 70 μm and a dynamic friction coefficient of 0.03 or less with respect to a stainless steel roll.

[0011] As the polybula alcohol-based resin used for the polybulualcohol-based film, a resin obtained by saponifying a polyacetic acid bull obtained by polymerizing a butyl acetate is usually used. However, the present invention is not necessarily limited to this, and it is also possible to use a resin obtained by saponifying a copolymer of butyl acetate and a component copolymerizable with a small amount of vinyl acetate. Examples of components copolymerizable with butyl acetate include unsaturated rubonic acid and its salts, esters, amides or -tolyl; olefins having 2 to 30 carbon atoms such as ethylene, propylene, n-butene and isobutene. Butyl ethers, unsaturated sulfonates, etc. can be used.

[0012] The weight average molecular weight of the polyvinyl alcohol-based resin is not particularly limited, but is preferably 120,000 to 300,000, more preferably <is 140,000 to 260000, and more preferably <is 16,000 to 200,000. When the weight average molecular weight force S is less than 120,000, sufficient optical performance cannot be obtained when a positive vinylenore n-nore-based resin is used as an optical film. When the film is a polarizing film, stretching becomes difficult, and industrial production is difficult and undesirable.

. In the present invention, the weight average molecular weight of the polyvinyl alcohol-based resin is GPC-

Means measured by LALLS method.

[0013] The saponification degree of the poly Bulle alcohol榭脂is preferably 97 to: LOO mol ^_0/0, more preferably 98 to: LOO mol ^_0/0, more preferably 99 to: in LOO mol% is there. If the saponification degree is less than 97 mol%, sufficient optical performance cannot be obtained when a poly (bull alcohol) resin is used as an optical film.

[0014] The method for producing the polybutyl alcohol film of the present invention is not particularly limited. For example, it can be produced by the following method for producing a polyvinyl alcohol film of the present invention.

[0015] The method for producing a polybulualcohol-based film of the present invention comprises (A) a step of preparing a polyvinyl alcohol-based rosin aqueous solution containing a surfactant and having a moisture content of 60 to 90% by weight, and (B ) A process for producing a polybulal alcohol film having a water content of 5% by weight or less from a polyvinyl alcohol-based resin aqueous solution by a casting method. The evaporation rate of the water in the fat aqueous solution is 15 to 30% by weight Z.

In the production method of the present invention, a surfactant is contained in the polyvinyl alcohol-based rosin aqueous solution in order to improve the slipping property of the film. As the surfactant, a commonly used non-ionic, cationic or cationic surfactant can be used. The surfactant used in the present invention is preferably a nitrogen-containing surfactant. The surfactant used in the present invention is preferably a non-ionic surfactant. It is particularly preferable to use a nonionic surfactant containing nitrogen, because it is easy to localize on the surface layer of the film after film formation. The mechanism of surfactant transfer to the film surface in the drying process is not clear, but as water moves to the surface of the polybulualcohol film, the surfactant with high affinity to water also moves to the surface. It is guessed.

[0017] As a non-ionic surfactant containing nitrogen,

Equation (1): I ^ CONH-R ² -OH (1)

A higher fatty acid monoal strength noramide represented by

Equation (2):

I ^ CON— (R ² — OH) (2)

2

A higher fatty acid dialkanolamide represented by

Equation (3):

R'CONH (3)

2

A higher fatty acid amide represented by

Equation (4):

R'NH (C H O) H (4)

2 4 X

Or formula (5):

H (CHO) yN (R ¹ ) (CHO) xH (5)

2 4 2 4

And polyoxyethylene alkylamine represented by the formula: In addition, polyoxyethylene higher fatty acid amides, amine oxides and the like can also be used.

In the formulas (1) to (5), R ¹ is an alkyl group or a alkenyl group having 6 to 22 carbon atoms, preferably 8 to 18 carbon atoms. If the alkyl group or alkenyl group has less than 6 carbon atoms, the surfactant tends to be insufficient in hydrophobicity, and if it exceeds 22, the surfactant tends to be insufficient in hydrophilicity. R ² is either —CH—, —CH— or —CH—

2 4 3 6 4 8

It is. Other than these alkylene groups, the hydrophilicity of the surfactant tends to be insufficient. X and y are integers of 1 to 20, and X and y may be the same as or different from each other. When at least one of X and y is an integer of 21 or more, there is a tendency that the compatibility between (polybulal alcohol-based rosin aqueous solution) and (surfactant) is poor. When such a surfactant is used, the alkyl group represented by R ¹ may be one type of alkyl group, or an alkyl group derived from palm oil, palm oil, palm kernel oil, beef tallow, etc. Like groups, alkyl groups having different carbon numbers may be mixed.

[0019] Specific examples of higher fatty acid alkanolamides include, for example, caproic acid mono- or diethanolamide, caproic acid mono- or dipropanolamide, caproic acid mono- or dibutanolamide, force prillic acid mono- or diethanolamide, force prill Acid mono or zip Ropanolamide, force prillic acid mono or dibutanol amide, force purinate mono or ethanol amide, force purinate mono or dipropanolamide, force purinate mono or dibutanol amide, lauric acid mono or diethanolamide, lauric acid mono or diprop Noramide, lauric acid mono or dibutanol amide, palmitic acid mono or diethanol amide, palmitic acid mono or dipropanolamide, palmitic acid mono or dibutanolamide, stearic acid mono or diethanolamide, stearic acid mono or dipropanolamide, stearin Acid mono or dibutanol amide, oleic acid mono or diethanolamide, oleic acid mono or dipropanolamide, oleic acid mono or Butanol amide, coconut oil fatty acid mono- or diethanolamide, coconut oil fatty acid mono- or di-propanol amide, coconut oil fatty acid mono- or di-butanol amide Nadogaa is down. Of these, lauric acid diethanolamide and palm oil fatty acid jetanolamide are preferably used.

[0020] Specific examples of higher fatty acid amides include, for example, cabronic acid amide, force prillic acid amide, force puric acid amide, lauric acid amide, palmitic acid amide, stearic acid amide, and oleic acid amide. Of these, palmitic acid amide and stearic acid amide are advantageously used.

[0021] Specific examples of polyoxyethylene alkylamines include, for example, polyoxyethylene hexylamine, polyoxyethylene heptylamine, polyoxyethyleneoctylamine, polyoxyethylene nonylamine, polyoxyethylene decylamine. , Polyoxyethyleneenddecylamine, polyoxyethylenetetradecylamine, polyoxyethylenehexadecylamine, polyoxyethyleneoctadecylamine, polyoxyethylene oleylamine, polyoxyethyleneeicosylamine and the like. Of these, polyoxyethylene dodecylamine is advantageously used.

[0022] Specific examples of the polyoxyethylene higher fatty acid amide include, for example, polyoxyethylene caproic acid amide, polyoxyethylene strength prillic acid amide, polyoxyethylene strength purinic acid amide, polyoxyethylene lauric acid amide, polyoxyethylene palmitic acid. Examples thereof include amides, polyoxyethylene stearic acid amides, and polyoxyethylene oleic acid amides. Among these, polyoxyethylene lauric acid amide, polyoxyethylene ester Aric acid amide is advantageously used.

[0023] Specific examples of the amine oxide include dimethyl lauryl amine oxide, dimethyl stearyl amine oxide, dihydroxyethyl lauryl amine oxide, and the like. Of these, dimethyllaurylamine oxide is advantageously used.

[0024] Among the nitrogen-containing surfactants, polyoxyethylene alkylamines, higher fatty acid amides and the like are particularly preferable in terms of compatibility between (polyvinyl alcohol-based rosin aqueous solution) and (surfactant). More preferably used.

[0025] The addition amount of the surfactant to the polybula alcohol-based rosin aqueous solution is preferably 0.01% by weight or more with respect to the polybulal alcohol-based rosin, and more preferably from 0.001 to It is 3% by weight, more preferably 0.03 to 2% by weight, particularly preferably 0.05 to 1% by weight. If the addition amount of the surfactant is less than 0.01% by weight, the amount of the surfactant in the vicinity of the surface of the produced film is insufficient and the effect of the present invention is poor. Conversely, if the amount of the surfactant added exceeds 3% by weight, the film surface appearance is unfavorable.

[0026] In the step (A), the method for preparing the polyvinyl alcohol-based resin aqueous solution is not particularly limited, and the polybulal alcohol-based resin fat wettable obtained by adjusting the water content of the polybulal alcohol-based resin. It is prepared by a method of dissolving the cake in water. It may be prepared using a multi-screw extruder. In addition, in a dissolving can equipped with an up-and-down circulating flow generating type stirring blade, water vapor is blown into the can to prepare a wet polyvinyl alcohol-based rosin wet cake. I can do it.

[0027] In addition to the polyvinyl alcohol-based resin and the surfactant, the polyvinyl alcohol-based resin aqueous solution includes general glycerin, diglycerin, triglycerin, ethylene glycol, triethylene glycol, polyethylene glycol and the like as necessary. From the viewpoint of mechanical properties and productivity, it is preferable to include a plasticizer that is commonly used. The addition amount of the plasticizer is preferably 30% by weight or less, more preferably 3 to 25% by weight, and still more preferably 5 to 20% by weight with respect to the polybulal alcohol-based resin. If the added amount exceeds 30% by weight, the strength of the produced film is inferior.

[0028] The water content (water content a described later, water content) of the polyvinyl alcohol-based aqueous resin solution used in the present invention thus obtained is 60 to 90% by weight (the resin concentration 40 to 10% by weight). , Preferably 65 to 85% (榭脂concentration 35-15 wt ^_0/0), which is especially 〖This preferably 70 to 80% (榭脂concentration 30 to 20% by weight). When the water content is less than 60% by weight, the viscosity of the aqueous solution becomes too high and uniform dissolution is difficult. Conversely, if the moisture content exceeds 90% by weight, it takes a long time to evaporate the moisture, resulting in poor productivity.

[0029] In order to control the evaporation rate of water in the drying process, the polyvinyl alcohol-based rosin aqueous solution may contain a small amount of auxiliary solvent in the range of 30 parts by weight or less to 100 parts by weight of water. . As co-solvents, methanol, ethanol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylol propane, dimethyl sulfoxide, N-methylpyrrolidone, ethylene diamine are preferred water-soluble solvents. , Diethylenetriamine, and mixtures thereof can be used.

[0030] Next, in the step (A), the polybulualcohol aqueous solution prepared in step (A) is usually defoamed. As the defoaming method, there are methods such as stationary defoaming and defoaming with a multi-screw extruder. The multi-screw extruder is not particularly limited as long as it is a multi-screw extruder having a vent, but usually a twin-screw extruder having a vent is used.

[0031] After the defoaming treatment, the polybulualcohol-based rosin aqueous solution is introduced into the T-shaped slit die in a certain amount. Thereafter, the polyvinyl alcohol-based aqueous resin solution discharged from the slit die is cast on a drum-type roll or an endless belt, and the film formed by the casting method is dried to have a moisture content of 5% by weight or less. (Process (B)).

[0032] Here, in casting a polybulualcohol-based rosin aqueous solution, a drum-type tool or endless belt is generally used. From the viewpoint of widening and lengthening the force, and uniformity of film thickness. It is preferable to use a mold roll.

[0033] In the production method of the present invention, the evaporation rate of water in the polybulualcohol-based rosin aqueous solution is adjusted to be 15 to 30% by weight Z. Here, the evaporation rate, the moisture content of the poly Bulle alcohol榭脂aqueous solution a (wt%) prepared in step (A), the water content of the film after drying b (weight ^_0/0), Poribyuru When the time from when the alcoholic resin solution is discharged to the drum-type tool to when the film finishes drying is defined as T (min), the value is expressed by the following formula (weight% Z min). . Evaporation rate = (a— b) ZT

[0034] In the production method of the present invention, the evaporation rate is adjusted to be 15 to 30 wt% Z, preferably 18 to 27 wt% Z, more preferably 20 to 25 wt% Z. Is done. It is believed that the faster the evaporation rate, the more effectively the surfactant moves to the vicinity of the film surface without diffusing and remaining in the produced film. When the evaporation rate is less than 15% by weight Z, the effect of improving slipperiness is not sufficient if the surfactant is not sufficiently transferred to the film surface. On the other hand, when the evaporation rate exceeds 30 wt% Z, the surface active agent bleeds out, and the surface smoothness of the film decreases and the film appearance such as whitening decreases. When the surfactant is sufficiently transferred to the vicinity of the film surface, a film roll and a metal roll made of stainless steel (hereinafter referred to as SUS) mainly used in each process of manufacturing the film or polarizing film, The slipperiness of the film is improved and the film surface is not damaged by contact with the metal roll.

[0035] The moisture content b of the polybutyl alcohol film after completion of drying is 5% by weight or less, preferably 4% by weight or less, more preferably 3% by weight or less. Further, the lower limit value of the moisture content b is preferably (0.5 wt%) or more. If the moisture content exceeds 5% by weight, it tends to cause wrinkles due to insufficient drying.

In the present invention, the moisture content b of the polybutyl alcohol film after completion of drying is measured as follows. That is, prepare a 15cm x 15cm film as the sample film, and measure the weight of this sample film (before drying under reduced pressure). The thickness of the sample film is not particularly limited as long as it is 30 to 70 / ζ πι. Next, this sample film is vacuum-dried at 83 ° C for 20 minutes in a vacuum dryer (vacuum level: lOmmHg or less), and the weight of the sample film after vacuum drying is measured. From the weight of the sample film before and after drying under reduced pressure, the moisture content b is calculated by the following formula. Moisture content b (%) = {(film weight before vacuum drying) one (film weight after vacuum drying) 100 / (film weight before vacuum drying) [0036] The evaporation rate is adjusted during the film forming process and the drying process. The evaporation rate in the film-forming process is mainly determined by the surface temperature of the drum-type roll and the force determined by the contact time between the polybulualcohol-based aqueous solution of resin and the drum-type roll. Also good. The surface temperature of the drum-type roll is preferably 70 to 100 ° C, more preferably 80 to 95 ° C, and still more preferably 85 to 95 ° C. Below 70 ° C, productivity is inferior, and above 100 ° C, bubbles are generated in the polyvinyl alcohol-based resin film. The contact time is preferably 30 to 240 seconds, more preferably 40 to 180 seconds, and still more preferably 50 to 120 seconds. If the contact time is less than 30 seconds, wrinkles are likely to occur in the drying process.

[0037] The method of drying performed after film formation is not particularly limited, and examples thereof include a method using a plurality of hot rolls and a method using a floating dryer. The drying temperature and drying time are not particularly limited as long as the water evaporation rate is 15 to 30% by weight Z, but the drying temperature is preferably in the range of 50 to 150 ° C.

[0038] In the present invention, the dynamic friction coefficient of the obtained polybulu alcohol-based film with respect to the stainless steel roll is 0.03 or less, preferably 0.01 to 0.03, particularly preferably 0.0. 02 to 0.03. In the present invention, the coefficient of dynamic friction of a film against a stainless steel roll means that a SUS304 test roll having a width of 40 mm, a diameter of 80 mm, a weight of 2. Okg, and a surface roughness (Ra) force of 0.05 m is moved on the film. The driving force F (kgf) force when rolling at lOOmmZ is also the rolling friction coefficient calculated by the following formula. μ = F / 2. 0 If the coefficient of dynamic friction is 0.03 or less, the film is transported with high productivity without causing cracks or wrinkles when it is transported between SUS rolls with a roll 'roll' roll. In addition, a polybutyl alcohol film free from optical defects can be obtained.

In the present invention, the surface roughness (Ra) is an arithmetic average roughness based on JIS B0601, and the surface roughness (Ra) 0.05 / zm of the test roll is a general optical Film transport and The value of the roll used for winding.

[0040] In addition, it is preferable that the polybulal alcohol film of the present invention has a surface roughness (Ra) of 0.05 μm or less, and particularly preferably 0.03 m or less. Is preferably from 0.01 to 0.02 μm. If the surface roughness (Ra) exceeds 0.05 μm, light scattering occurs on the film surface, which is not preferable.

[0041] The total light transmittance of the polybutyl alcohol film of the present invention is preferably 90% or more, more preferably 91% or more. The upper limit of the total light transmittance is 95%.

[0042] Tensile strength of poly Bulle alcohol film of the present invention, more preferably the preferred instrument 75NZmm ² or more it is 70NZmm ² or more. The upper limit of the tensile strength, preferably have 115NZmm ² below instrument l lONZmm ² or less being more preferred. The tensile strength in the present invention refers to a tensile strength obtained by performing a tensile test at a tensile speed of lOOOOmmZmin on a test piece conditioned for 24 hours in a 20 ° C 65% RH environment. It is strength.

[0043] The complete dissolution temperature of the polybutyl alcohol film of the present invention is preferably 65 ° C or higher, more preferably 65 to 90 ° C, and more preferably 71 to 80 ° C. In the present invention, the complete dissolution temperature means that 2000 ml of water is put into a 2 L beaker, heated to 30 ° C., then a 2 cm × 2 cm film piece is added and stirred at a rate of 3 ° CZ. This is the temperature at which the film dissolves completely when the water temperature is raised. The thickness of the film piece is not particularly limited as long as it is 30 to 70 / ζ πι.

[0044] Further, the polybulal alcohol film of the present invention has a thickness of 30 to 70 µm, preferably 35 to 55 µm, particularly preferably 40 to 50 µm. If the thickness force is less than 30 μm, it is difficult to stretch the polarizing film, and sufficient polarizing performance cannot be obtained. When a film is bonded to a liquid crystal panel, white spots are likely to occur over time, and inconveniences such as deterioration of the display quality of the panel are likely to occur.

[0045] In the polybulualcohol-based film of the present invention, the force with which the width and length are arbitrary. In view of the recent increase in width and length, the width is preferably 2 m or more, more preferably 2. It is preferably 5 m or more, particularly preferably 3 m or more, and the length is preferably 1000 m or more, more preferably 2000 m or more, particularly preferably 3000 m or more, and particularly preferably 4000 m or more in terms of productivity of the polarizing film. More preferably, it is 4000-15000m. If the width is less than 2 m or the length is less than 1000 m, the productivity of the polarizing film is poor.

[0046] The polybulualcohol-based film of the present invention has sufficient smoothness and appearance as an optical film, and is preferably used as a raw film in optical production, particularly in the production of a polarizing film. The film thickness of the polybulal alcohol film used for the production of the polarizing film is 30 to 70 μm, preferably 35 to 55 μm, and particularly preferably 40 to 50 μm, as described above.

[0047] The polarizing film of the present invention is produced by using the above-described polybulualcohol-based film through processes such as normal dyeing, stretching, boric acid crosslinking, and heat treatment. The polarizing film can be manufactured by stretching a polybulualcohol-based film, immersing it in an iodine or dichroic dye solution and dyeing it, then treating it with a boron compound, and simultaneously stretching and dyeing. There are a method of compound treatment, a method of dyeing with iodine or a dichroic dye and stretching and then a method of treating with boron compound, a method of dyeing and then stretching in a solution of boron compound, etc. it can. As described above, the polyvinyl alcohol-based film (unstretched film) may be stretched and dyed and further subjected to boron compound treatment separately or simultaneously. However, at least one of the dyeing step and the boron compound treatment step may be performed. It is desirable from the point of productivity to carry out uniaxial stretching.

[0048] Stretching is desirably performed in a uniaxial direction by 3 to 10 times, preferably 3.5 to 6 times. At this time, a slight stretching (stretching to prevent shrinkage in the width direction or more) may be performed in a direction perpendicular to the stretching direction. It is desirable to select a temperature of 40 to 170 ° C as the temperature during stretching. Furthermore, if the draw ratio is finally set within the above range, the drawing operation may be carried out not only in one stage but also in any stage of the manufacturing process.

[0049] The film is generally dyed by bringing the film into contact with a liquid containing iodine or a dichroic dye. Usually, an aqueous solution of potassium monoiodide is used, the iodine concentration is 0.1 to 20 gZL, the potassium iodide concentration is 10 to 70 gZL, and the potassium iodide Z iodine weight ratio is 10 to L00. It is preferable. Dyeing time is 30 ~ 500 Seconds are practical. The temperature of the treatment bath is preferably 5 to 60 ° C. The aqueous solution may contain a small amount of an organic solvent compatible with water in addition to the aqueous solvent. As the contact means, any means such as dipping, coating, spraying and the like can be applied.

[0050] The dyed film is generally then treated with a boron compound. Boric acid and borax are practical as boron compounds. It is practically desirable that a small amount of potassium iodide coexist in the liquid in which the boron compound is preferably used in the form of an aqueous solution or a water-organic solvent mixture at a concentration of about 0.3 to 2 mol ZL. The treatment method is preferably an immersion method, but of course, a coating method and a spraying method can also be implemented. The treatment temperature is preferably about 40 to 70 ° C, and the treatment time is preferably about 2 to 20 minutes. If necessary, the stretching operation may be performed during the treatment.

[0051] The polarization degree of the polarizing film of the present invention thus obtained is preferably 98 to 99.9%, more preferably 99 to 99.9%. If the degree of polarization is less than 98%, the contrast of the liquid crystal display is lowered, which is not preferable.

[0052] The single transmittance of the polarizing film of the present invention is preferably 43% or more. If it is less than 43%, it tends to be impossible to achieve high brightness of the liquid crystal display. The upper limit of the single transmittance of the polarizing film is 46%.

[0053] The polarizing film of the present invention can also be used as a polarizing plate having a protective film on one side or both sides thereof. The protective film is preferably an optically isotropic polymer film or polymer sheet. As the protective film, for example, cellulose triacetate, cellulose diacetate, polycarbonate, polymethyl methacrylate, polystyrene, polyether sulfonate, polyarylene ester, poly-4-methylpentene, polyphenylene oxide, cyclo or norbornene polyolefin Film or sheet

[0054] In addition, for the purpose of thin film, the polarizing film is coated with a curable resin such as urethane resin, acrylic resin, and urea resin on one or both sides instead of the protective film. Then, it can be done by stacking.

[0055] The polarizing film (including at least one surface laminated with a protective film or a curable resin) has a method in which a transparent pressure-sensitive adhesive layer is usually known on one surface as necessary. In some cases, it is formed and used for practical use. Examples of pressure-sensitive adhesive layers include acrylic acid esters such as butyl acrylate, ethyl acrylate, methyl acrylate, 2-ethylhexyl acrylate, and acrylic acid, maleic acid, itaconic acid, methacrylic acid, and the like. A polarizing film is mainly composed of a copolymer with a monoolefin carboxylic acid such as crotonic acid (including those containing a butyl monomer such as acrylic-tolyl, butyl acetate and styrene). It is particularly preferable because it does not inhibit the polarization characteristics of the resin, but any pressure-sensitive adhesive having transparency that is not limited to this can be used. For example, polyvinyl ether or rubber may be used.

[0056] Further, various functional layers can be provided on one side (the side not provided with the pressure-sensitive adhesive) of the polarizing film (one provided with the pressure-sensitive adhesive). Examples of the functional layer include an antiglare layer, a hard coat layer, an antireflection layer, a half reflection layer, a reflective layer, a phosphorescent layer, a diffusion layer, an electoluminescence layer, a viewing angle expansion layer, and a brightness enhancement layer. . It is also possible to combine two or more types, for example, an antiglare layer and an antireflection layer, a phosphorescent layer and a reflective layer, a phosphorescent layer and a half reflection layer, a phosphorescent layer and a light diffusion layer, a phosphorescent layer and an electoluminescence A combination of a layer, a half-reflective layer, and an electoluminescence layer. However, it is not limited to these.

[0057] The polarizing film of the present invention includes an electronic desk calculator, an electronic watch, a word processor, a personal computer, a portable information terminal, a liquid crystal display device such as an instrument for automobiles and machinery, sunglasses, eye protection glasses, solid glasses, It is preferably used for reflection-reducing layers for display elements (CRT, LCD, etc.), medical equipment, building materials, and toys.

Example

Hereinafter, embodiments of the present invention will be described in detail based on examples, but the present invention is not limited to these examples.

In the examples, the weight average molecular weight of the polyvinyl alcohol-based resin, the coefficient of dynamic friction between the polyvinyl alcohol-based film and the stainless steel roll, and the surface roughness Ra of the polybulur alcohol-based film were determined by the following methods.

[0059] (1) Weight average molecular weight The weight average molecular weight is measured by the GPC-LALLS method under the following conditions.

[0060] 1) GPC

Equipment: Waters Model 244 gel permeation chromatograph

Column: TSK-gel—GMPWXL manufactured by Tosoh Corporation (inner diameter 8 mm, length 30 cm, 2 pcs) Solvent: 0.1 M—Tris buffer (pH 7.9)

Flow rate: 0.5mlZ min

Temperature: 23 ° C

Sample concentration: 0.040%

Filtration: Tosoh Co., Ltd. 0.45 m Mysori Disc W— 25-5

Injection volume: 0.2 ml

Detection sensitivity (differential refractive index detector): 4 times

[0061] 2) LALLS

Equipment: Chromatrix KMX—Type 6 Low Angle Laser Light Scattering Photometer

Temperature: 23 ° C

Wavelength: 633nm

Second virial coefficient X concentration: OmolZg

Refractive index concentration change (dnZdc): 0.159ml / g

Filter: Made by MILLIPORE 0.45 μm filter HAWPO 1300

Gain: 800mV

[0062] (2) Coefficient of dynamic friction

A strip-shaped test piece having a width of 40 mm and a length of 100 mm was left in a 23 ° C, 50% RH environment for 1 day, then placed on a flat board, and in that environment, on the test piece, Roll a SUS304 roll of width 40mm, diameter 80mm, weight 2.0kg, surface roughness Ra force .05m at a speed of 100mm Z and a distance of 70mm. The driving force F (kgf) at that time is measured with Shimadzu Corporation auto-draft AGS-H, and the dynamic friction coefficient is obtained according to the following equation.

μ = F / 2. 0

[0063] (3) Surface roughness (Ra)

Measured with a laser focus microscope VK-8500 manufactured by Keyence Corporation. Measurement The conditions are as follows.

Measurement length: 0.3 mm, objective lens: 50 times, cutoff: 0.8 m, smoothing: none [0064] [Example 1]

(Manufacture of polybulu alcohol film)

500L tank, put 200kg of water at 18 ° C, stir, add 40kg of polybulal alcohol-based resin with weight average molecular weight of 142,000 and ken degree of 99.8 mol%, and continue stirring for 15 minutes It was. Then, after draining water, 200 kg of water was further added and stirred for 15 minutes. The resulting slurry was dehydrated to obtain a polyvinyl alcohol-based榭脂Uettoke rk in water of 40 weight ^_0/0.

[0065] 67 kg of the obtained polybulu alcohol-based rosin wet cake was put into a dissolution can, 4.2 kg of glycerin as a plasticizer, and polyoxyethylene alkylamine as a surfactant (in the formula (5), R ¹ is CH, x and y are 1) Hold 28g and 10kg of water, steam from the bottom of the can

12 25

Infused. Stirring (rotation speed: 5 rpm) was performed when the internal resin temperature reached 50 ° C, and the system was pressurized when the internal resin temperature reached 100 ° C. After the temperature was raised to 150 ° C., the blowing of water vapor was stopped (the total amount of water vapor was 90 kg), and stirring was performed for 30 minutes (rotation speed: 20 rpm). After uniformly dissolving, a polyvinyl alcohol-based aqueous resin solution having a moisture content of 74% by weight was obtained.

Next, after defoaming the obtained polyvinyl alcohol-based resin aqueous solution (liquid temperature: 147 ° C.) with a twin-screw extruder, it is transferred to a drum-type roll from a T-type slit die (straight-mould hold die). Discharge (liquid temperature 95 ° C) and cast to form a film. The conditions for casting film formation were as follows.

[0067] Drum type ronore

Diameter: 3200mm, width: 4000mm, rotation speed: 10mZ min, surface temperature: 95 ° C, contact time: 54 seconds

The moisture content of the obtained film immediately after casting was 20% by weight. Continuously, the membrane was dried at 100 ° C. for 111 seconds by a floating dryer (length: 18.5 m) blowing hot air on both sides. The resulting polybulal alcohol film (width 3000 mm, thickness 50 m, length 4000 m) had a moisture content of 4% by weight, and the time from discharge to the end of drying was 165 seconds (water evaporation rate 25 wt. % Z min). [0068] The resulting film had a dynamic friction coefficient of 0.021 and a surface roughness (Ra) of 0.03 μm.

[0069] (Production of polarizing film)

The obtained polybulal alcohol film was immersed in an aqueous solution of 0.2 g of iodine / 15 g of potassium iodide at 30 ° C. for 240 seconds, and then an aqueous solution having a composition of boric acid 60 gZL and potassium iodide 30 gZL (55 Boric acid treatment was carried out for 5 minutes while uniaxially stretching 4 times. Then, it dried and obtained the polarizing film. The optical defects of the obtained polarizing film were evaluated as follows. The results are shown in Table 2.

[0070] (Optical defects)

Optical linear defects on the surface of the polarizing film were observed using a light box with a surface illuminance of 14,000 lux and evaluated according to the following criteria.

〇 ...

X ...

[0071] [Examples 2 to 5]

A polybulu alcohol film was obtained in the same manner as in Example 1 except for the conditions shown in Table 1. Table 2 shows the dynamic friction coefficient and surface roughness of the film obtained.

[0072] A polarizing film was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0073] [Example 6]

A polybutyl alcohol film was obtained in the same manner as in Example 1 except that a polyvinyl alcohol resin having a weight average molecular weight of 175000 was used. Table 2 shows the dynamic friction coefficient and surface roughness of the film obtained.

In addition, a polarizing film was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0075] [Comparative Examples 1-2]

Further, a polarizing film was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. The results are shown in Table 2. Show.

[0077] [Comparative Example 3]

A polybulu alcohol film was obtained in the same manner as in Example 1 except for the conditions shown in Table 1. However, the surface active agent was deposited on the film surface, and the film appearance was whitened.

[0078] [Table

[0079] [Table 2]

Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. [0081] This application is based on a Japanese patent application filed on November 2, 2004 (Japanese Patent Application No. 2004-319264) and a Japanese patent application filed on December 10, 2004 (Japanese Patent Application No. 2004-357945). The contents of which are incorporated herein by reference.

Industrial applicability

[0082] According to the present invention, it is possible to obtain a polybulualcohol-based film having excellent transport performance and no optical defects. In addition, the polybulualcohol film of the present invention is a polybulcoalcoholic film without optical defects, and is effective as a raw film for a polarizing film.

Claims

The scope of the claims

[1] The film thickness is 30-70 μm and the dynamic friction coefficient for the stainless steel roll is

0.03 or less polybulal alcohol film.

[2] The polybulualcohol-based film according to claim 1, which contains a polybulualcohol-based resin having a weight average molecular weight of 140000 to 260000.

[3] The polybule alcohol based vinyl resin according to claim 1, wherein the surface roughness (Ra) is 0.05 μm or less.

[4] The polybutyl alcohol film according to [1], wherein the film width is 2 m or more.

[5] The polybulu alcohol-based finem according to claim 1, wherein the film has a length of 4000 m or more.

6. The polyvinyl alcohol-based Finolem according to claim 1, which is used as a raw film for a polarizing film.

[7] (A) a step of preparing a polybulal alcohol-based rosin aqueous solution containing a surfactant and having a moisture content of 60 to 90% by weight; and

(B) A step of producing a polyvinyl alcohol film having a water content of 5% by weight or less from the aqueous polyvinyl alcohol resin solution by a casting method.

A method for producing a polybulualcohol-based film having

A method for producing a polyvinyl alcohol film, wherein the step of producing the polyvinyl alcohol film is carried out so that the evaporation rate of water in the polyvinyl alcohol-based resin aqueous solution is 15 to 30% by weight Z.

[8] The surfactant is a surfactant containing nitrogen,

The method for producing a poly (vinyl alcohol) film according to claim 7, wherein the surfactant is contained in the polyvinyl alcohol-based resin aqueous solution in an amount of 0.01% by weight or more based on the polyvinyl alcohol-based resin.

[9] The method for producing a polybulualcohol film according to [7], wherein the surfactant is a nonionic surfactant containing nitrogen.

[10] (A) a step of preparing a polybulualcohol-based rosin aqueous solution containing a surfactant and having a moisture content of 60 to 90% by weight; and (B) A step of producing a polyvinyl alcohol film having a water content of 5% by weight or less from the aqueous polyvinyl alcohol resin solution by a casting method.

A method for producing a polybulualcohol-based film having

The step of producing the polyvinyl alcohol film is performed such that the evaporation rate of water in the polyvinyl alcohol resin aqueous solution is 15 to 30% by weight Z; Item 8. A method for producing a polybulualcohol film, which is the polybulualcohol film according to item 1.

[11] The surfactant is a nitrogen-containing surfactant,

11. The method for producing a poly (vinyl alcohol) film according to claim 10, wherein the surfactant is contained in the polyvinyl alcohol-based resin aqueous solution in an amount of 0.01% by weight or more based on the polyvinyl alcohol-based resin.

12. The method for producing a polyvinyl alcohol film according to claim 10, wherein the surfactant is a nonionic surfactant containing nitrogen.

[13] A polarizing film formed on the polyvinyl alcohol film according to [1].

14. A polarizing plate comprising the polarizing film according to claim 13, and a protective film provided on at least one surface of the polarizing film.